It is common in the production field to use a reciprocating pumping system to pump the production fluid from the well up to the surface. In such a system a reciprocating pump on the surface drives the production string up and down, causing the production fluid to be sucked up. In the down stroke, a check or one-way ball valve prevents the fluid from escaping back down into the hole.
On occasion it is necessary or desirable to inject or circulate a fluid down into the hole and around the foundation of the production zone, such as various chemicals, steam, etc. In the prior art, for such to take place, the production operator had to pull the entire production string out of the hole and bring in a separate work-over rig at very great cost (e.g. $5,000 to $20,000/day) requiring relatively highly skilled engineers and causing a substantial amount of down time (e.g. two and a half days). Such is has been a very expensive, time consuming operation.
Using the tool and methodology of the present invention, all of this is avoided, with substantial savings in energy production costs. With the invention's tool at the end of the production string, the operator using, for example, two rough-necks or roustabouts, basically merely changes the state of the tool from its production flow or pumping disposition to its fluid injection state by merely twisting the internal part of the tool down in the hole by, for example, about ninety (90.degree.) degrees, and allowing or causing an internal part to longitudinally move with respect to the outer part(s), and injecting the fluid down through the production string. Once the fluid is injected, the rough-necks or roustabouts merely twist the tool back to its production state and re-initiate production, all with relatively little down time and relatively little expense.
Additionally, another problem resolved with the present invention has been the long standing problem of the pollution and possible toxic damage done to workers in the pulling of production strings up from the hole. Because of the nature of the prior art, down-hole, in-line, dual ball valve system, when a production string was pulled up from the hole, it would be filled with production fluid that would come flowing out onto the ground and the workers, as each section of the tubing was unmade on the surface. Indeed, laws have been passed making this practice illegal.
In contrast, in the present invention, the special tool of the invention is locked into its "open" disposition, so that, when the production string is pulled, the in-line proiluction fluid merely flows out of the bottom of the string as it is raised, allowing a "dry" string to be pulled. The use of the invention greatly diminishes, if not completely avoids, this significant, prior art pollution problem.
For general informational purposes, it is noted that the inventor hereof became aware of a nonback-wash tool, designed by Spears Specialty Oil Tools, Inc. of Tomball, Tex., in which tool there were two, in-line ball valves, in which the bottom one was designed to be hocked off of its seat, when so desired, by the use of a downwardly and sidewardly moving, spoon-like structure, which didn't work satisfactorily and only provided a relatively small opening rather than the full bottom opening of the present invention.
Thus, in contrast, the present invention overcomes the prior art problems by providing a down-hole circulation system which is safe, reliable, easy and inexpensive to use, saving many thousands of dollars on a regular basis over the prior art approaches, while also providing significant energy savings and enhanced pollution prevention.